Enhanced NH and NO sensing performance of TiCO MXene by biaxial strain: insights from first-principles calculations.

In this study, we investigate the adsorption properties of CO, NH, and NO gases on TiCO MXene surfaces through density functional theory (DFT) calculations. A comprehensive analysis of the adsorption preferences, electronic properties, work function (), sensitivity (), and recovery time () was conducted, focusing on the effects of biaxial strain () ranging from -2% to 4%. At free strain, toxic gases can adsorb onto the TiCO surface, with adsorption energies () of -0.096 eV (CO), -0.344 eV (NH), and -0.349 eV (NO), indicating moderate interactions between NH, NO and the TiCO surface, while CO displays weaker physisorption. Electron density difference (EDD) and electron localization function (ELF) analyses underscore the electron transfer mechanisms, supporting the enhanced sensitivity of TiCO for NH and NO detection. The influence of on gas adsorption behaviour was also studied, demonstrating that tensile strain enhances NH adsorption ( = -0.551 eV at = 4%), while NO exhibits an inverse trend under compressive strain ( = -0.403 eV at = -2%). The based on a change rate of was evaluated to be around 12% and 6% for NH and NO, respectively, within the calculated strain range, indicating sufficient detection capability. Additionally, the for NH and NO detection was computed. At 0% strain and 300 K, the values for NH and NO are in the microsecond range, suggesting that detecting these gases under normal conditions poses a challenge. However, strain-tuned TiCO and lowered temperature enhance the gas sensing performance, with increased values at tensile strain for NH and compressive strain for NO. These results suggest that TiCO MXene, when tuned with biaxial strain, is a promising candidate for detecting NH and NO at low to room temperatures.